48 OUTLINES OF ENTOMOLOGY. 



mons. The head is broad, connected with the thorax by a very short 

 neck, and the abdomen is sessile: i. e., joins the thorax by a wide base 

 instead of a slender stalk. 



The larvse are much more independent than those of the higher 

 families of the Order. They are not confined to cells or chambers, and 

 the only provision made for them by the parent insect is the insertion 

 of her eggs in the kind of leaves or wood which her young require for 

 food. They subsist entirely upon vegetation, and are separated into 

 two families : 



1st. Saw-tlies (Tenthredintdje), and 



2d. Horn-tails or Wood-borers (Urocerid^). 



The Saw-flies are easily lecognized by their broad, thin wings, 

 which are divided into numerous cells by fine veins or nervures, and 

 by the soft and yielding integument of the body. The antennoe are 

 usually short and simple, varying in the females in the number of joints. 

 A few species have these organs knobbed at the tip or toothed or 

 feathered on one edge. The ovipositor, from the peculiar structure of 

 which these insects derive their popular name, consists of two saw- 

 like blades, the sides of which are ridged and the lower edges finely 

 serrated or notched. The blades are strengthened by a back so grooved 

 that they can slide back and forth upon it. When not in use they are 

 protected by a sheath and concealed in an opening on the under side of 

 the abdomen. With this most ingenioas instrument the insect saws 

 little oblique slits in the cuticle of leaves or in the principal veins, in 

 which she places her eggs. There are some exceptions to this rule, 

 found among species that are very prolific and destructive : e. g., the 

 Imported Currant-worm, in which the eggs are attached externally to 

 the veins of the leaf and kept in place by a sticky fluid which is exuded 

 with them. In such species the ovipositor is found to have lost, in 

 great measure, its saw-like character. The Saw-flies are slow and heavy 

 in flight, sluggish in all their motions and easily captured. 



The larvae are called "slugs" and "false caterpillars," and are 

 classed with the most destructive of insect pests. The Imported and 

 the Native Currant-worms, the Rose slug, the Pear slug, the White 

 Pine and the Larch false caterpillars are some of the most pernicious 

 species. They are of elongate, worm-like form, with large, roundish, 

 glossy heads, on some of which are seen a pair of antennre-like pro- 

 cesses. The thoracic legs are well developed, and the hinder end of 

 the body is supported upon six to eight pairs of fleshy points or props, 

 which differ from the pro-legs of genuine caterpillars, not only in their 

 greater number, but in lacking the little circle of hooks by which the 

 latter can so firmly attach themselves to any surface. In some of these 



